白酒酿造过程酒醅中尿素的控制与减少

尿素是白酒酿造过程酒醅中含有的氨基甲酸乙酯的主要前体之一,对浓香型白酒中氨基甲酸乙酯含量影响较大,通过降低酒醅中尿素含量可以控制或减少白酒中氨基甲酸乙酯的含量。采用产脲酶菌株或其粗酶与酒醅混合,可在发酵过程中降低尿素含量。从大曲中筛选到3株产脲酶的腐生葡萄球菌(Staphylococcus saprophyticus,S.saprophyticus)在酒醅固态发酵中去除尿素效果不显著,产酸性脲酶的罗伊氏乳杆菌(Lactobacillus reuteri,L.reuteri)全细胞及其粗酶对酒醅中尿素均有很好的去除效果。通过与商品脲酶比较,罗伊氏乳杆菌所产脲酶粗酶对酒醅中尿素去除效果更佳,尿素去除率可达100%。当罗伊氏乳杆菌添加量高于10~7CFU/g酒醅时,尿素去除率在97.3%以上,粗酶加入量高于25 U/kg酒醅时,尿素去除率在77.4%以上。罗伊氏乳杆菌能较好地去除白酒酒醅中尿素。     

白酒固态发酵过程中不同品种高粱原料对氨基甲酸乙酯形成的影响

氨基甲酸乙酯(EC)是一种致癌物质,广泛存在于乙醇饮料中。为明确高粱原料对白酒固态发酵过程中EC形成的影响,从而为降低白酒中EC含量提供理论指导,通过模拟白酒固态发酵,分析了不同品种高粱原料发酵过程中EC及其前体物质的变化规律。结果表明,固态发酵过程中糯高粱S3对应的最终EC产量(4.27 mg/kg)高于粳高粱S1(4.06 mg/kg)和S2(4.21 mg/kg),且其EC平均形成速率是粳高粱S1(0.22 mg/kg/d)和S2(0.24 mg/kg/d)的1.6倍。对EC前体物质研究发现,瓜氨酸和尿素是高粱固态发酵过程中EC形成的主要前体物质,其中瓜氨酸可能对S1和S2发酵产EC的贡献较大,而尿素则对S3发酵产EC的贡献较大。此外,在整个固态发酵过程中,氰化物并未参与EC的形成。研究表明,不同品种高粱原料对固态发酵过程中产EC的影响差异显著,选择合适的高粱品种,控制高粱原料所带入的EC前体物质的含量,可有效控制白酒固态发酵过程中的EC含量。     

浓香型和芝麻香型白酒酒醅中微生物菌群的研究

对白酒窖池发酵的全程跟踪取样,借助于PCR-变性梯度凝胶电泳(DGGE)和16S rRNA基因文库两种方法,对比研究了江苏地区浓香型和芝麻香型白酒酒醅在发酵过程中的微生物茵群结构.DGGE图谱分析显示,随着发酵时间的延长,酒醅中的微生物多样性不断降低;发酵结束时Lactobacillus manihouvorans成为最主要的优势菌种.16S rRNA克隆文库的测序结果在数据库中进行比对后表明,浓香型和芝麻香型酒醅中的微生物种属存在巨大差异,仅有Weissella、Bacillus、Acetobacter和Lactobacillus 4个属的微生物在两个文库中均能检测到,发现并鉴定出在白酒曲药和酒醅的研究中尚未报道的细菌属.     

小窖芝麻香型白酒蒸馏过程中氨基甲酸乙酯的研究

建立了气相色谱-质谱(GC-MS)法定量白酒中氨基甲酸乙酯(EC,ethyl carbamate)的分析方法,并对小窖芝麻香型白酒在蒸馏过程中不同馏分EC含量的变化规律进行了分析研究。结果表明,该方法线性关系大于0.999,定量限低至1.98μg/L,相对标准偏差(RSD,relative standard deviation)为0.51%~1.17%,不同样品中EC的回收率在92%~113%之间。该方法简单、快速、灵敏、准确度高,满足白酒中EC的检测要求。小窖芝麻香型白酒中各馏分酒EC含量相对较低,且不同发酵层次酒醅的馏分中EC含量的变化呈现明显规律,其中在面糟馏分中的EC含量最高,其次是中糟馏分,底糟馏分最低。此外,面糟和中糟馏分中的EC含量在蒸馏过程中呈现下降趋势。快速分析芝麻香型白酒蒸馏过程中EC含量的变化规律,为探索白酒中EC的可能来源及降除方法提供了依据。     

酒醅发酵过程中氨基甲酸乙酯与尿素的变化

摘要：建立超声萃取固体基质样品,顶空固相微萃取技术（HS—SPME）结合气相色谱-质谱（GC—MS）检测白酒大曲和酒醅中氨基甲酸乙酯（EC）的方法。采用比色法测定白酒大曲和酒醅中尿素浓度。结果表明,不同香型酒醅中尿素和EC的变化趋势类似,且二者之间具有一定相互关系．发酵结束时,酒醅中EC浓度在110-130μg／kg,尿素浓度26-80mg／kg。     

降解浓香型白酒中氨基甲酸乙酯菌株的筛选及产酶特性研究

氨基甲酸乙酯(Ethyl carbamate,EC)是一种可致癌物质,普遍存在于发酵食品中,研究如何降低发酵食品中EC的含量对提高发酵食品的安全性具有重要意义。该研究采用高通量筛选技术,从浓香型白酒酒醅中分离得到1株能够同时降低EC及其前体尿素的解淀粉芽孢杆菌JP21。将该菌株用于模拟白酒窖内发酵,发酵结束时酒醅中的尿素和EC分别减少了12%和17%,并且对酒醅中挥发性物质无显著影响。通过对该菌株所产EC和尿素降解酶进行初步纯化及酶学性质研究,发现该酶对尿素和EC均有降解作用。酶的最适反应p H值为5.5,最适反应温度为35℃,可耐受低浓度乙醇。研究采用发酵食品体系内源微生物干预的方法,实现了对混菌发酵体系中氨(胺)类危害物的有效减控。     

两种堆积醅对芝麻香型白酒发酵特性和香气品质的影响

高温堆积是芝麻香型白酒生产的关键工艺,其效果直接影响后续发酵及最终酒样质量。受温度和氧浓度影响,堆积结束时,表层醅和中心醅中酵母和细菌数量不同,两者的糖化酶、淀粉、酸度、还原糖和酒度也存在明显差异。为探讨2种不同堆积醅对芝麻香型白酒生产的影响,通过实验室控温模拟窖内发酵实际温度变化,将表层醅和中心醅按不同混合比例混合后进行对比发酵。研究发酵过程理化指标动态变化,并应用气相色谱-质谱联用(gas chromatography-mass spectrometer,GC-MS)结合感官品评分析最终酒样。实验结果表明,不同混合比例酒醅理化指标变化存在差异;实际生产混合酒醅控温发酵所得酒样最接近工厂原酒样;中心醅占比较大的酒醅所产酒具有芝麻香型酒风味特征,推测中心醅与芝麻香型白酒典型风味形成关系较大。     

浓香型白酒发酵过程中氨基甲酸乙酯形成的关联因子探究

浓香型白酒中氨基甲酸乙酯（EC）影响其安全性。该实验考察了浓香型白酒发酵过程中酒醅EC含量分别与环境因子及微生物的相关性。结果表明，EC含量随着发酵时间的延长呈上升趋势，主要发生在发酵的中后期；pH与EC含量呈负相关，系数为0.9，而水分则与EC含量呈正相关，相关系数为0.83，温度和乙醇含量对EC的形成有一定的促进作用，相关系数分别为0.48和0.71。此外，发酵体系中乳杆菌属（Lactobacillus）和和酿酒酵母属（Saccharomyces）与EC含量的相关系数为0.97和0.96，两者的丰度越高，EC越容易积累；芽孢杆菌属（Bacillus）则对EC的合成起到反作用，与EC含量的相关系数为0.78。因此可在浓香型白酒的发酵期间人为调控pH值、水分含量及上调芽孢杆菌属在发酵微生物中的比例，达到降低EC含量的目的。     

浓香型白酒酿造过程中不同形态氰化物的含量分布规律

氰化物作为我国白酒中一类具有直接和间接安全风险的内源性危害物,研究其在酿造过程中的形成规律是进行科学减控的基础。该研究建立了基于QuEChERS-气相色谱-质谱联用(QuEChERS-gas chromatograph-mass spectrometer, QuEChERS-GC/MS)技术测定酒醅中不同形态氰化物的技术方法,并对不同工艺浓香型白酒酿造过程中不同形态氰化物分布规律进行了研究。结果显示,浓香型白酒酒醅中存在着不同形态的氰化物,包括氰苷、非糖苷和游离形态。浓香型白酒酿造原料种类配比特别是高粱原料品种及用量,影响着酿造过程中氰化物的初始引入量。在发酵阶段,氰苷发生降解,非糖苷形态与游离形态的氰化物含量有明显差异,窖池发酵过程可能存在着氰醇;在蒸馏阶段,非糖苷形态氰化物发生进一步的分解。酒醅中不同形态氰化物含量分布趋势均呈现上层<中层<下层,蒸得的原酒中游离氰化物与氨基甲酸乙酯(ethyl carbamate, EC)的含量分布趋势与酒醅一致。该研究结果为浓香型白酒生产降低氰化物与调控EC的研究提供基础数据参考。     

不同香型白酒中氨基甲酸乙酯的研究与风险评估

主要对不同香型白酒中的氨基甲酸乙酯(ethyl carbamate,EC)含量进行分析,包括浓香、酱香、清香、兼香、芝麻香、药香、凤香、老白干香、豉香和特香型原酒和成品酒(n=342)。检测结果显示,白酒中EC检出率为100%。原酒中EC平均含量最高的为凤香型原酒(822.23μg/L);其次是特香型原酒(339.34μg/L);第三是浓香型原酒(298.21μg/L),药香型原酒中EC平均含量最低(80.32μg/L)。成品酒中EC平均含量最高的是芝麻香型白酒(214.13μg/L);其次是浓香型白酒(191.89μg/L);第三是凤香型白酒(168.24μg/L),清香型白酒中EC平均含量最低(46.23μg/L)。EC含量分布统计显示,所检测的成品酒中48.7%的样品中EC含量超过了加拿大、巴西、日本等国家谷物蒸馏酒的EC限量标准(150μg/L)。采用暴露边界比(Margin of Exposure,MOE)对成品白酒中EC进行风险评估,MOE值为6289,具有致癌风险。此研究期望为我国食品安全部门制定饮料酒中EC的限量标准提供有效的参考。     

Reliable identification of grapevine rootstock varieties using RAPD PCR on woody samples

Since grapevine ( Vitis spp .) rootstock material is being traded increasingly as disbudded woody material a lack of distinctive morphological features on such material necessitates an alternative and reliable means of identification. Methods described here were developed for rapid and efficient extraction of DNA from woody samples rich in phenolic compounds and polysaccharides, and for subsequent identification of varieties by RAPD PCR. Using these methods, and with the application of only one selected RAPD primer, we were able to differentiate sixteen rootstock varieties, including the seven varieties most commonly used in Germany. Problems commonly encountered with reproducibility of RAPD patterns were avoided by choosing primers with a dinucleotide sequence and a high G/C content that allowed a rather high annealing temperature of 45°C. Methods described here should also be useful for other horticultural crops, especially those with woody tissues rich in phenolic compounds and polysaccharides.     

An internet compendium of analytical methods and spectroscopic information for monomers and additives used in food packaging plastics

An internet website (http://cpf.jrc.it/smt/) has been produced as a means of dissemination of methods of analysis and supporting spectroscopic information on monomers and additives used for food contact materials (principally packaging). The site which is aimed primarily at assisting food control laboratories in the European Union contains analytical information on monomers, starting substances and additives used in the manufacture of plastics materials. A searchable index is provided giving PM and CAS numbers for each of 255 substances. For each substance a data sheet gives regulatory information, chemical structures, physico-chemical information and background information on the use of the substance in particular plastics, and the food packaging applications. For monomers and starting substances (155 compounds) the infra-red and mass spectra are provided, and for additives (100 compounds); additionally proton NMR are available for about 50% of the entries. Where analytical methods have been developed for determining these substances as residual amounts in plastics or as trace amounts in food simulants these methods are also on the website. All information is provided in portable document file (PDF) format which means that high quality copies can be readily printed, using freely available Adobe Acrobat Reader software. The website will in future be maintained and up-dated by the European Commission's Joint Research Centre (JRC) as new substances are authorized for use by the European Commission (DG-ENTR formerly DGIII). Where analytical laboratories (food control or other) require reference substances these can be obtained free-ofcharge from a reference collection housed at the JRC and maintained in conjunction with this website compendium.     

Aroma characterization of various apricot varieties using headspace–solid phase microextraction combined with gas chromatography–mass spectrometry and gas chromatography–olfactometry

The characterization of the aromatic profile of several apricot cultivars with molecular tracers in order to obtain objective data concerning the aromatic quality of this fruit was undertaken using headspace–solid phase microextraction (HS–SPME). Six apricot cultivars were selected according to their organoleptic characteristics: Iranien, Orangered, Goldrich, Hargrand, Rouge du Roussillon and A4025. The aromatic intensity of these varieties measured by HS–SPME–Olfactometry were defined and classified according to the presence and the intensity of grassy, fruity and apricot like notes. In the six varieties, 23 common volatile compounds were identified by HS–SPME–GC–MS. Finally, 10 compounds, ethyl acetate, hexyl acetate, limonene, β-cyclocitral, γ-decalactone, 6-methyl-5-hepten-2-one, linalool, β-ionone, menthone and (E)-hexen-2-al were recognized by HS–SPME–GC–O as responsible of the aromatic notes involved in apricot aroma and considered as molecular tracers of apricot aromatic quality which could be utilized to discriminate apricot varieties.     

Tests of potential functional barriers for laminated multilayer food packages. Part I: Low molecular weight permeants

The advent of the functional barrier concept in food packaging has brought with it a requirement for fast tests of permeation through potential barrier materials. In such tests it would be convenient for both foodstuffs and materials below the functional barrier (sub-barrier materials) to be represented by standard simulants. By means of inverse gas chromatography, liquid paraffin spiked with appropriate permeants was considered as a potential simulant of sub-barrier materials based on polypropylene (PP) or similar polyolefins. Experiments were performed to characterize the kinetics of the permeation of low molecular weight model permeants (octene, toluene and isopropanol) from liquid paraffin, through a surrogate potential functional barrier (25 μm-thick oriented PP) into the food simulants olive oil and 3% (w/v) acetic acid. These permeation results were interpreted in terms of three permeation kinetic models regarding the solubility of a particular model permeant in the post-barrier medium (i.e. the food simulant). The results obtained justify the development and evaluation of liquid sub-barrier simulants that would allow flexible yet rigorous testing of new laminated multilayer packaging materials.     

Analysis of benzo[a]pyrene in spiked fatty foods by second derivative synchronous spectrofluorimetry after microwave-assisted treatment of samples

A simple, rapid and inexpensive method has been developed for the determination of benzo[a     

The development of reference materials for paralytic shellfish poisoning toxins in lyophilized mussel. II: Certification study

This paper describes the second part of a project undertaken to develop certified mussel reference materials for paralytic shellfish poisoning toxins. In the first part two interlaboratory studies were undertaken to investigate the performance of the analytical methodology for several PSP toxins, in particular saxitoxin and decarbamoyl-saxitoxin in lyophilized mussels, and to set criteria for the acceptance of results to be applied during the certification exercise. Fifteen laboratories participated in this certification study and were asked to measure saxitoxin and decarbamoyl-saxitoxin in rehydrated lyophilized mussel material and in a saxitoxin-enriched mussel material. The participants were allowed to use a method of their choice but with an extraction procedure to be strictly followed. The study included extra experiments to verify the detection limits for both saxitoxin and decarbamoyl-saxitoxin. Most participants (13 of 15) were able to meet all the criteria set for the certification study. Results for saxitoxin.2HCl yielded a certified mass fraction of <0.07 mg/kg in the rehydrated lyophilized mussels. Results obtained for decarbamoyl-saxitoxin.2HCl yielded a certified mass fraction of 1.59+/-0.20 mg/kg. The results for saxitoxin.2HCl in enriched blank mussel yielded a certified mass fraction of 0.48 +/- 0.06 mg/kg. These certified reference materials for paralytic shellfish poisoning toxins in lyophilized mussel material are the first available for laboratories to test their method for accuracy and performance.     

Announcing a new international peer-reviewed journal:Food Science and Human Wellness now accepting manuscript submission in English

<正>We are pleased to announce the launch of a new international peer-reviewed journal-Food Science and Human Wellness,ISSN 2213-4530,which is an open access journal,produced and hosted by Elsevier B.V.on behalf of Beijing Academy of Food Sciences.Food Science and Human Wellness is an international peer-reviewed English journal that provides a forum for the dissemination of the     

Chinese CTP Market

According to Printing and Printing Equipment Industries Association of China（PEIAC）＇s statistics to the plate manufucturer in China, in 2013, the actual offset plate production has reached 346 million square meters in China. Among them, the CTP production volume was 245 million square meters, up by 11% than that of last year; the total sales of the CTP plate was 239 million square meters, up by 13%.     

Preparatory Work of Print China 2015 is Going Smoothly

正Held at Guangdong Modern International Exhibition Center,Print China 2015 will cover 7exhibition halls,besides the original Hall No.3,4,5,6,7,the newly built F zone of Hall 3 will be used too.The total area will be140,000 square meters.Hall 3:Offset and large printing equipment,package printing equipment,post press